Phase Noise Monitoring in Cascaded Systems for High-Resolution Automotive Radar Sensors

The trend toward a higher degree of automation in modern cars demands radar sensors providing a significantly increased angular resolution. This is achieved by increasing the number of transmit and receive channels, which is most commonly done by cascading several radar monolithic microwave integrated circuits (MMICs). As for single MMIC radar solutions, the phase noise (PN) contained in the transmit signal is one of the most dominant signal distortions limiting detection sensitivity and range also in cascaded radar systems. In this work, we present a novel method to estimate the mean PN power spectral density (PSD) of two radar MMICs in operation. This estimation result is used to detect whether the frequency-generating circuit of the involved MMICs generate PN out of specification. Different to most of the existing methods, the proposed approach is based on an application relevant frequency modulated continuous wave (FMCW) signal, which is actually used to perform a radar measurement, instead of a continuous wave (CW) signal. Finally, the presented concept is verified based on simulations and with the help of measurement data.